﻿var SellerScroll = function(options){
	this.SetOptions(options);
	this.lButton = this.options.lButton;
	this.rButton = this.options.rButton;
	this.oList = this.options.oList;
	this.showSum = this.options.showSum;
	
	this.iList = $("#" + this.options.oList + " > li");
	this.iListSum = this.iList.length;
	this.iListWidth = this.iList.outerWidth(true);
	this.moveWidth = this.iListWidth * this.showSum;
	
	this.dividers = Math.ceil(this.iListSum / this.showSum);	//共分为多少块
	this.moveMaxOffset = (this.dividers - 1) * this.moveWidth;
	this.LeftScroll();
	this.RightScroll();
};
SellerScroll.prototype = {
    SetOptions: function (options) {
        this.options = {
            lButton: "left_scroll",
            rButton: "right_scroll",
            oList: "carousel_ul",
            showSum: 4	//一次滚动多少个items
        };
        $.extend(this.options, options || {});
    },
    ReturnLeft: function () {
        return isNaN(parseInt($("#" + this.oList).css("left"))) ? 0 : parseInt($("#" + this.oList).css("left"));
    },
    LeftScroll: function () {  
        if (this.dividers == 1) return;
        var _this = this, currentOffset;
        $("#" + this.lButton).click(function () {
            currentOffset = _this.ReturnLeft();
            if (currentOffset == 0) {
                for (var i = 1; i <= _this.showSum; i++) {
                    $(_this.iList[_this.iListSum - i]).prependTo($("#" + _this.oList));
                }
                $("#" + _this.oList).css({ left: -_this.moveWidth });
                $("#" + _this.oList + ":not(:animated)").animate({ left: "+=" + _this.moveWidth }, { duration: "slow", complete: function () {
                    for (var j = _this.showSum + 1; j <= _this.iListSum; j++) {
                        $(_this.iList[_this.iListSum - j]).prependTo($("#" + _this.oList));
                    }
                    $("#" + _this.oList).css({ left: -_this.moveWidth * (_this.dividers - 1) });
                }
                });
            } else {
                $("#" + _this.oList + ":not(:animated)").animate({ left: "+=" + _this.moveWidth }, "slow");
            }
        });
    },
    RightScroll: function () {
        if (this.dividers == 1) return;
        var _this = this, currentOffset;
        $("#" + this.rButton).click(function () {
            currentOffset = _this.ReturnLeft();
            if (Math.abs(currentOffset) >= _this.moveMaxOffset) {
                for (var i = 0; i < _this.showSum; i++) {
                    $(_this.iList[i]).appendTo($("#" + _this.oList));
                }
                $("#" + _this.oList).css({ left: -_this.moveWidth * (_this.dividers - 2) });

                $("#" + _this.oList + ":not(:animated)").animate({ left: "-=" + _this.moveWidth }, { duration: "slow", complete: function () {
                    for (var j = _this.showSum; j < _this.iListSum; j++) {
                        $(_this.iList[j]).appendTo($("#" + _this.oList));
                    }
                    $("#" + _this.oList).css({ left: 0 });
                }
                });
            } else {
                $("#" + _this.oList + ":not(:animated)").animate({ left: "-=" + _this.moveWidth }, "slow");
            }
        });
    }
};
$(document).ready(function () {
    var ff = new SellerScroll();
});